iOS App Programming: Objective-C and Other Useful Tools

Objective-C is the premier programming language used in software programming for iOS and Mac OS X and our app developers know it inside and out. Sure, you can create iOS apps using other languages ​​and technologies, such as C ++, PyObjC, MacRuby, Pure C, or MonoTouch, but these alternatives are better for additional features or for other purposes. When going about programming in iOS, you cannot do without the ideal language.

Web-based solutions

Another option to program an app is to design a non-native web-based program that looks like a native mobile iOS app, but is actually a site accessed through a web browser.

Do I really need to learn Objective-C?

If you are completely satisfied with the functionality of your web-based apps, you can bypass Learning Objective-C and familiarize yourself with the Cocoa Framework instead of reading this guide. It's best to use tutorials on app-based programming in HTML but on the other hand, if you want to program high-quality native apps for the iOS mobile operating system, these guides will help you do just that.

The Objective-C Programming Language

Objective-C is a generic, object-oriented programming language that is basically an extension of the C programming language. It adds many features to the C environment, such as Smalltalk style messaging, multiple inheritance, runtime reflection, and more. It has a noticeably different syntax than other languages, so if you're familiar with languages ​​like Java or Ruby, it can seem strange at first glance. Objective-C is a superset of C that creates the opportunity to get return to C when writing iOS apps. For example, you can easily find native C data types and native function calls in iOS and Mac apps as well as code written in Objective-C.

Classes, objects and methods

If your iOS app knowledges needs refreshing, Magora developers have prepared a brief tutorial on classes, objects, and methods explaining what they are and how to use them in Objective-C. Classes are plans that define a set of goals and behaviors for the object to be created. Classes usually correspond to concepts in the real world, such as Plant.

Plants are able to recognize certain variables, such as color, height and species, as well as behaviors such as flowering, reproduction and photosynthesis. An object belonging to a class is an instance of this class and each instance has its own set of variables. As an example, you can create 200 instances in a Plant class and define different variables for each of them. The method is the behavior of an instance of a class or class. They are therefore called class methods and instance methods.

Now let's make sure you understand what that means. Do you know what square brackets are? Get ready to use them a lot in Objective-C because they contain method calls. On the left, you can see that we've built a new variable for Plant * called ourPlant, and on the right we've made two method calls and defined how they are returned to our Plant.

If you use a variable of some specific size during the build phase, it will be stored on the stack. This stack provides storage for local data and is accessible without pointers. For example, the stack stores basic data types, such as Long, Boolean, Byte, char, int, short, etc., because they all have a default maximum size. The size of objects in Objective-C is unrestricted and grows as needed, which is why they should be stored in the heap for dynamic memory allocation and the use of pointers. A pointer is a memory address, and if you need to access anything contained in memory, you must dereference the pointer.

How to build an instance

The heap is the memory in which all Objective-C objects are stored, for the purpose of dynamic allocation. All objects are pointers to the heap, indicated by asterisks.

How to make method calls in iOS

If you're still not sure what's happening, take a closer look at the process of invoking a method. Plant Allocation means that we'll call the class method of the Plant + alloc class. The class method always has a plus sign. It is used to return the ID of a generic type. Using -init means that we call an instance method to initialize memory to gain access to the new object. The indicator of the instance method is the minus sign before. Objects cannot be used without performing both operations.

When dealing with objects, and assigning a certain amount of memory, use an object. Notify the execution time when it is released. With this language, you can use one object with several elements of the current iOS application using the reference counting system. The use of each object is tracked and counted because it can be used once by different elements of an iOS app.

When you are programming an object, it has only one reference. When a part of an iOS app is completed using the object, it sends a "release" message, resulting in a reduction in the number of references. When no references are left, the memory is released.

If you neglect to free up the memory of an object that is no longer in use, it may cause the iOS app to crash or run poorly because the program will be using too many features. With Mac apps, it not only can cause a crash, but can also slow down the entire system and consume excessive memory. There is no doubt that you've experienced this type of problem by leaving Safari running for a few days or trying to keep a game working in the background while running other programs. This is because iOS apps use exponentially more memory the longer they operate and leave almost no resources to run other programs free. Memory is one of the most important features for iOS app developers, so use it wisely. The Apple Memory Management Guide is a great resource to help you gain a deeper understanding of Cocoa memory management.

The object can store data, regardless of its behavior. There are several types of data attributes:

  • Model name
  • Manufacturer
  • Color
  • Operational system

Now we must study these properties. The first is the name of the template. It can be expressed as a combination of numbers. The data type of this attribute is a number. You can use a different method to represent a number:

  • As a primitive int
  • As an instance of the NSNumber class
  • The NSInteger data type in the Foundation

As you can see, you have at least three options. Now let's explain what they mean. The first option is the NSNumber class defined in the Foundation structure. The second is an int variable type which is a primitive kind of data in C that contains a number with the maximum value. The third is an NSInteger of the basic data type, which also comes from the Foundation framework. Its size can be adapted to the needs of an iOS program at any given time. The Foundation is one of the frameworks for programming Apple iOS apps.

You don't need to allocate memory for int or NSInteger as their size is already set. None of the other elements declared in the Foundation Data Types Reference, such as NSInteger, CGSize, CGPoint, CGRect, are objects, so they also do not require an asterisk pointer.

Let's go back to the first case where the 1900738 model is stored as an NSNumber object. It is not necessary to configure memory and return it with this object because they have a convenient class method to facilitate automation.

iOS App Programming with Professionals

We program high-quality iOS apps that stand out thanks to their incredible designs, feature rich environments and excellent user experiences. The developers at Magora are committed to their process and have delivered hundreds of successful B2C iOS programs, custom enterprise systems, initial MVPs and beautiful sites designed for a broad spectrum of industries. At Magora, the cornerstone of our culture is perfect communication with customers, total process transparency and strong teamwork. Contact us to discuss your thoughts - We would be happy to receive your comments over the phone, read your email correspondence or meet you at our London headquarters.

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